A geometry can provide, and a shader program can use, more than one source of texture coordinates for each vertex. Use this key to specify which geometry source should provide data for each texture sampler vertex attribute declared in a shader program. The mapping channel for a geometry source corresponds to its index in the array returned by calling the geometrySourcesForSemantic: method.
A 4 x 4 matrix for transforming coordinates from scene (or world) space to view (or eye) space.
This documentation contains preliminary information about an API or technology in development. This information is subject to change, and software implemented according to this documentation should be tested with final operating system software.